(1) Field of the Invention
The invention relates to an oven for continuous baking of baked goods, such as bread, Viennese bread, pastry products and the like, comprising a baking chamber and conveying means for holders, such as plates, racks or the like, on which are arranged said products, these conveying means being capable of taking over these holders through the baking chamber, to convey them from an inlet opening to the outlet opening of same.
(2) Description of the Prior Art
In the field of industrial bakery, the equipment used should be capable of meeting increasingly higher production cycles. To this end, there have been developped ovens for continuous baking which, though being effectively capable of adapting themselves to the desired production speeds, have a number of drawbacks related to their size and weight.
As a matter of fact, such known ovens often include a parallelepipedically shaped insulating jacket inside which defines a baking chamber provided with an inlet opening and an outlet opening and through which pass conveying means which allow the conveying of the holders, such as plates, racks or the like, on which are arranged the products to be baked.
Thus, some ovens, called tunnel-ovens, include a linear baking chamber through which passes a conveyer on which are arranged the holders, such as plates or the like.
There are also known conveying means in the shape of one or several norias arranged inside the baking chamber. This or these norias are provided with brackets onto which are positioned said plates in order to ensure their transfer from the inlet opening to the outlet opening through imparting to same an upward and/or a downward motion inside said baking chamber. From this prior document is in particular known a noria comprised of a pair of motor-driven and juxtaposed chains describing a looped circuit and defining an upward chain side and a downward chain side. Furthermore, to these chains are perpendicularly secured brackets on which rest the plates with products to be baked. Because of this design, there are inside the oven a column of upwardly moving plates and a column of downwardly moving plates, it being known that, once it arrives at the upper end of the noria, a plate located on the ascending column is transferred onto the brackets of the descending column through appropiate transfer means.
These known ovens include large-capacity baking chambers, so that they are inevitably heavy and cumbersome, which presently means a lot of drawbacks.
Thus, in order to solve the problem of transport sizes and to avoid the use of very large handling devices or even simply for reasons of difficulty of access to the rooms where it will be used, the manufacturer is obliged to ship an oven for continuous baking as spare parts. Therefore, after having been delivered to the user, these spare parts must be assembled by a team of skilled installers. This results into mounting and commissioning sites for long periods, with, accordingly, an expensive immobilization of the equipment and the places of the future operation.
Such known large production-capacity ovens for continuous baking have, in addition, a number of drawbacks related to their lack of flexibility in use. In particular, because of the absence of compartmentation and control, it is difficult to efficiently separate the atmosphere at the beginning, at half-way and at the end of baking of the products. Now, for some products, it is necessary to modulate the parameters, such as temperature and humidity, according to whether the baking is in its initial or final phase. By way of an example, for making fully baked loaves, it is necessary to start baking in a high-temperature and steam-saturated atmosphere and the temperature and humidity should be decreasing at half-way, then at the end of the baking process. In comparison, for making only pre-baked loaves which are intended for being deep-frozen, there is required a lower, but rather constant temperature combined with a very high steam saturation inside the whole of the oven.
These known ovens for continuous baking are also incapable of adapting themselves to changes in production rhythm. Considering the above-mentioned example, there is required two to three times less time for pre-baking a product than for ensuring the full baking of the same product. Thus, assuming the shaping and trimming machines which precede the oven in a production line are used at full capacity for making fully baked loaves and this equipment cannot produce more pieces when turning to the manufacturing of pre-baked loaves, the oven for continuous baking will be half or up to two thirds empty, in order to meet, in this case, the baking time for these pre-baked loaves. In order to achieve a reduction of the baking time in an oven for continuous baking, the speed of the conveying means which convey the products from the inlet to the outlet of the oven is indeeed increased. As already stated above, for their baking, the bread, Viennese bread, pastry products or the like are arranged on holders, such as plates or racks. Now, since they are always supplied at the same rhythm by the machines located upstream, these plates or racks are farther separated from each other inside the oven when the aforementioned requirements have to be met, i.e. when the baking time has to be reduced by increasing the speed of the conveying means inside the oven. This generally results into an uneveness of baking of the products arranged on the plates, without taking into consideration that the complete oven has to be heated and supplied with steam, which is obviously not optimal as regards the energy consumption.
Another drawback of these known ovens for continuous baking resides in the almost impossible access to the products contained in the oven in the event of an unexpected stopping of the means ensuring the conveying of the products through this oven, e.g., due to an interruption of energy supply.
Finally, one should appreciate that because of the large size and the heavy weight of such ovens or because of the assembling structure or even because of the presence of a heating system installed in the lower portion, these ovens directly rest on the floor. Now, in the case of automatic production lines, this arrangement entails the looping of the conveying circuit for the baking holders, such as plates, racks or the like, either by passing above the oven or by turning around the latter, creating an additional occupation of the working room and, in some cases, impeding the free access to the side walls of the oven at which it often includes auxiliary devices or hatches for looking inside the oven.